Tunable optical matter: electrostatic repulsion modulates near- and far-field gold nanoparticle arrangements

Year: 2025

Type: article

Abstract: The dynamics and equilibrium configurations of immersed optically-bound particles are complex phenomena involving several physical mechanisms such as optical forces, electrostatic interactions, and fluid dynamics. In this work, we unravel, using experiments and numerical simulations, the key role played by short-range electrostatic forces. The repulsive interaction among gold nanoparticles is adjusted by changing the salt concentration. When the electrostatic interaction is reduced, near-field optical binding with particles oriented along the polarization direction is promoted, while, for low values of the salt concentration, inter-particle repulsion induces far-field (FF) optical binding configurations oriented perpendicular to the polarization. The importance of electrostatic force is confirmed by a theoretical model in which the repulsive effect is explicitly tuned. The numerical results reproduce the measured particle configurations and highlight the dominant role of electrostatic interactions, particularly in FF optical binding configurations.

Source: Nanoscale Advances

DOI: 10.1039/d5na00926j

Authors: Jim Jui-Kai Chen, Jorge Olmos-Trigo, Boris Louis, Chih-Hao Huang, Susana Rocha, Hiroshi Masuhara, Johan Hofkens, Rafael Delgado-Buscalioni, Roger Bresolí-Obach, Manuel I. Marqués, Marc Mélendez

Institutions: KU Leuven, Universidad de La Laguna, National Yang Ming Chiao Tung University, Max Planck Institute for Polymer Research, Universidad Autónoma de Madrid, Institut Químic de Sarrià, Universitat Ramon Llull

Language: English

Topic: Orbital Angular Momentum in Optics

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,962

Funders: European Commission, Shanghai Educational Development Foundation, Fonds Wetenschappelijk Onderzoek, KU Leuven, Onderzoeksraad, KU Leuven, Ministry of Education, India, Vlaamse regering, National Science and Technology Council, HORIZON EUROPE Framework Programme, Agencia Estatal de Investigación, Hsinchu Science Park Bureau, Ministry of Science and Technology, Taiwan, H2020 Marie Skłodowska-Curie Actions, HORIZON EUROPE European Innovation Council

OpenAlex ID: W7117565575